Method for installing a large-span cylindrical reticulated shell

ABSTRACT

A method of construction and installation of a large-span cylindrical reticulated shell comprises: installing a mother vault on the ground by a bulk method; pushing the mother vault gradually during the installation, so as to be match with a lifting device for lifting the extension tail end of the mother vault; adjusting the height of the extension tail end to allow the extension tail end to be maintained at a ground level for ground installation construction; and after the installation of the mother vault is completed, using a high-altitude overhanging construction method to install the other reticulated vaults adjacent to the mother vault, respectively, in sequence along the axial extending direction of the mother vault until the completion of installation of the entire large-span cylindrical reticulated shell is completed.

TECHNICAL FIELD

The invention relates to a method of construction and installation of a large-span cylindrical reticulated shell structure, in particular to a method for installing a large-span cylindrical reticulated shell.

BACKGROUND

A heat power plant often needs a dry coal shed with net span of more than 76 meters generally, and sometimes even more than 100 meters because of the usage of coal stoker. The net height is above twenty-eight meters generally. A scientific, economical and reasonable scheme for the large-span closed shed with a great height is a cylindrical reticulated shell, which has been validated through calculation of mathematical theory and mechanical theory. However, the installation process is a changing and developing process. The expenses and construction periods vary with different installation processes, thus the effect is different. Traditional construction processes include an overall scaffold construction method and a local scaffold construction method. In the overall scaffold construction method, the scaffold is required to be built in the coverage area of the entire cylindrical reticulated shell, thus the construction period is long, and the cost is high; in the local scaffold construction method, firstly, the scaffold is built for installing an anchor ring, and the anchor ring extends towards two sides by adopting a high-altitude overhanging construction method based on the anchor ring. Since only partial scaffolds are required to be built, the local scaffold construction method is favorable for reducing the construction period and the construction cost. For example, Chinese Patent Application No. 200810231497.2, entitled “A High-Altitude Overhanging Construction Method for a Cylindrical Shell Type Bolted Ball Joint Net Frame” discloses a local scaffold construction method. However, a scaffold with a height equivalent to the highest position of the cylindrical reticulated shell has to be built even in the local scaffold construction method, and as to the extra-large and extra-high cylindrical reticulated shells, the construction cost and the construction difficulty are still relatively high.

SUMMARY

The invention provides a method for installing a large-span cylindrical reticulated shell. A scaffold is not required to be built, and a crane is used as an auxiliary tool, therefore the method is simple and practical and has high reliability, low cost and short construction period.

To achieve its purposes, the invention adopts the following technical scheme:

The method for installing a large-span cylindrical reticulated shell comprises the following steps:

A) The large-span cylindrical reticulated shell is divided into a plurality of axially arranged reticulated vaults according to the supporting conditions, and each reticulated vault at least comprises four support bases (1) symmetrically arranged on both sides of the reticulated vault and ball joints and pull rods which are respectively installed on the four support bases (1) and mutually connected into a net frame shape; firstly, a reticulated vault is installed and called as a mother vault, a rotatable ball joint (2) is respectively installed on the support base (1) on any side of the mother vault, and then other ball joints and pull rods on the mother vault are respectively installed in sequence by taking the rotatable ball joint (2) as the starting point; the mother vault which should be installed in a vertical high-altitude extending manner is installed in a transverse extending manner during the installation of the ball joints and the pull rods, and a lifting device (3) is used for lifting the extension tail end of the mother vault during the transverse extending process of the mother vault, so that the height of the extension tail end always meets the requirement of ground installation construction;

B) After the completion of connection between all the ball joints and pull rods on the mother vault, the ball joint in the symmetrical position of the rotatable ball joint (2) is fixed on the support base in the corresponding position, i.e., the installation of the entire mother vault is completed; a high-altitude overhanging construction method is adopted after the completion of installation of the mother vault, and other reticulated vaults adjacent to the mother vault are respectively installed in sequence along the axial extending direction of the mother vault until the completion of installation of the entire large-span cylindrical reticulated shell.

The rotatable ball joint (2) is rotatably installed on the support base (1) during the installation of the mother vault; the rotatable ball joint (2) is fixed with the support base after the completion of installation of the reticulated vaults and before the completion of installation of the entire large-span cylindrical reticulated shell.

By adopting the technical scheme, in the installation process, the scaffold is not required, and the crane and other lifting devices are used as auxiliary tools, therefore, the installation process is simple and practical and is highly reliable, with a low cost and a short construction period.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an elevational view of an embodiment of the large-span cylindrical reticulated shell ;

FIG. 2 is an elevational view of the mother vault when the mother vault is being installed;

FIG. 3 is an elevational view of the mother vault at the last stage of the assembling process;

FIG. 4 is an elevational view of the mother vault after the assembling process is completed.

FIG. 5 is a schematic view of the support base and a ball joint.

FIG. 6 is a schematic view of a ball joint.

FIG. 7 is a schematic view showing a high altitude overhanging construction method.

FIG. 8 is a schematic view of a finished structure by a method of installing a large-span cylindrical reticulated shell.

DETAILED DESCRIPTION

As shown in the drawings, the method for installing the large-span cylindrical reticulated shell comprises the following steps:

A) The large-span cylindrical reticulated shell is divided into a plurality of axially arranged reticulated vaults according to the supporting conditions, and each reticulated vault at least comprises four support bases (1) symmetrically arranged on both sides of the reticulated vault and ball joints and pull rods which are respectively installed on the four support bases (1) and mutually connected into a net shape frame; firstly, a reticulated vault called a mother vault is installed, two support bases (1) are respectively arranged on both sides of the mother vault in the embodiment, and a rotatable ball joint (2) is respectively installed on the support base (1) on any side of the mother vault; the rotatable ball joint (2) is rotatably installed on the support base (1). The specific structure is as follows: the rotatable ball joint (2) can be bound on the support base (1) through a chain or a steel wire rope. As shown in FIG. 5, one end of the steel wire rope (7) is connected to the support base (1), and the other end movably holds the ball joint (2). Alternatively, a deeper ball socket is directly arranged at the top end of the support base (1), and the rotatable ball joint (2) is installed in the ball socket; the rotatable ball joint (2) can be installed at the top end of the support base (1) by adopting the two methods above, which can rotate, but cannot fall off from the support base (1).

After the completion of installation of the rotatable ball joint (2), other ball joints and pull rods on the mother vault are respectively installed in sequence by taking the rotatable ball joint (2) as the starting point; when the ball joints and the pull rods are installed, the mother vault which should be installed in a vertical high-altitude extending manner is installed in a transverse extending manner, so that the mother vault can be installed on the ground, and a scaffold is not required to be built. Because the mother vault has a certain radian, the installation of the ball joint and the pull rod is blocked by the ground or a construction platform with the progress of installation and the transverse extending process of the mother vault. A lifting device (3) is used for properly lifting the extension tail end of the mother vault at the moment, so that the height of the extension tail end always allows the installation construction to be performed on the ground level, and the rotatable ball joint (2) gradually rotates to the designed angle along the rise of the extension tail end. The lifting device (3) can adopt various devices capable of raising the height such as cranes, hoists, hydraulic jacks, chain blocks and the like. The mother vault is hung in the position where the stress is most reasonable, and the deformation is smallest during the lifting process according to the force principle.

B) After the completion of connection between all the ball joints and pull rods of the mother vault, the ball joint in the symmetrical position of the rotatable ball joint (2) is fixed on the support base, i.e., the installation of the entire mother vault is completed; after the completion of installation of the mother vault, the rotatable ball joint (2) can be fixed with the support base (1), by a fastening method, e.g., a welding method.

The installed mother vault is the first vault. After the installation of the mother vault, a high-altitude overhanging construction method is adopted to install the other reticulated vaults one by one longitudinally.

Within each reticulated vault, after the installation of a top ball joint 51 in a bottom circumferential vault line, the very adjacent bottom ball joint 52 in a top circumferential vault line will be installed. This step is repeated until the whole reticulated vault is finished.

As shown in FIG. 6, ball joints and pull rods are manufactured before the installation. Based on the supporting requirement, the whole large-span cylindrical reticulated shell is longitudinally divided into several reticulated vaults. The span of each reticulated vault is equal to the designed span of the reticulated shell. Before installation, every ball joint (5) is connected to one circumferential vertical chord rod, one circumferential chord rod, and two flank rod to form an installing unit containing one ball and four rods. A crane is then used to lift a unit to the proper installation position in the air, then the unit is connected to other installed units. Similarly, other reticulated vaults adjacent to the mother vault are respectively installed in sequence in an axially extending direction of the mother vault until the completion of the installation of the entire large-span cylindrical reticulated shell.

As shown in FIG. 7, J, L and N are top circumferential vault lines, which contains top ball joints J1, J1+1, J1−1, L1, L1+1, L1−1, N1, N1+1 and N1−1; K, M are bottom circumferential vault lines, which contains bottom ball joints K1, K1−1, M1, and M1−1. The solid lines indicate the part where ball joints and pull rods have been installed on the top circumferential vault lines J and L, and the bottom circumferential vault line K in the mother vault. The dashed lines indicate the uninstalled parts in the top circumferential vault line N and the bottom circumferential vault line M.

Using the installation of a ball joint to a bottom circumferential vault line M as an example, each ball joint is connected to the corresponding rods on the ground to form an installation unit with one ball and four rods according to design requirements. For example, the ball joint on the bottom circumferential line M1 is connected to a vertical rod M1K1, a bottom circumferential chord rod M1M1−1 and two flank rods M1L1 and M1L1+1 to form an unit of one ball and four rods. The unit is then lifted to its corresponding installation position. Four workers at the positions of K1, L1, L1−1, M1−1 that already have ball joints then connect the other ends of the four rods to the corresponding installed ball joints on the bottom circumferential lines K1, L1, L1−1 and M1−1, and tight the bolts. After confirming the quality of the connection, the connection of the bottom circumferential line ball joint M1 and its corresponding rods is finished. The installation is then moved to the very next ball joint on the bottom circumferential line M1−1. After installing all the ball joints on the bottom circumferential line M and confirming the quality of the installation, the ball joints on the immediately adjacent top circumferential line N are then installed.

Each ball joint on the top circumferential line N is connected to corresponding rods on the ground to form an installation unit with one ball and four rods according to design requirements. For example, the ball joint on the top circumferential line N1 is connected to a top circumferential vertical rod N1L1, a bottom circumferential chord rod N1N1−1 and two flank rods N1M1−1 and N1M1 to form a unit of one ball and four rods. The unit is then lifted to its corresponding installation position. Four workers at the positions of L1, M1−1, M1, and N1−1 that already have ball joints then connect the other ends of the four rods to the corresponding installed ball joints on the top circumferential lines L1, M1−1, M1 and N1−1, and tight the bolts. After confirming the quality of the connection, the connection of the top circumferential line ball joint N1 and its corresponding rods is finished. The installation is then moved to the next ball joint on the top circumferential line N1−1.

The same procedure is repeated to finish the whole circumferential line. Then the installation is moved to the next vault until the whole reticulated shell as shown in FIG. 8 is finished. 

1. A method for installing a large-span cylindrical reticulated shell, comprising: A) the large-span cylindrical reticulated shell is divided into a plurality of axially arranged reticulated vaults according to the supporting conditions, and each reticulated vault at least comprises four support bases symmetrically arranged on both sides of the reticulated vault and ball joints and pull rods which are respectively installed on the four support bases and mutually connected into a net frame shape; firstly, a reticulated vault is installed and called as a mother vault, a rotatable ball joint is respectively installed on the support base on any side of the mother vault, and then other ball joints and pull rods on the mother vault are respectively installed in sequence by taking the rotatable ball joint as the starting point; the mother vault which should be installed in a vertical high-altitude extending manner is installed in a transverse extending manner during the installation of the ball joints and the pull rods, and a lifting device is used for lifting the extension tail end of the mother vault during the transverse extending process of the mother vault, so that the height of the extension tail end always meets the recruitment of ground installation construction; B) after the completion of connection between all the ball joints and pull rods on the mother vault, the ball joint in the symmetrical position of the rotatable ball joint is fixed on the support base in the corresponding position, i.e., the installation of the entire mother vault is completed; a high-altitude overhanging method is adopted for construction after the completion of installation of the mother vault, and other reticulated vaults adjacent to the mother vault are respectively installed in sequence along the axial extending direction of the mother vault until the completion of installation of the entire large-span cylindrical reticulated shell.
 2. A method for installing a large-span cylindrical reticulated shell according to claim 1, wherein, the rotatable ball joint is rotatably installed on the support base during the installation of the mother vault; the rotatable ball joint is fixed with the support base after the completion of installation of the reticulated vaults and before the completion of installation of the entire large-span cylindrical reticulated shell.
 3. A method for installing a vault of a large-span cylindrical reticulated shell, comprising: installing a rotatable ball joint on a support base; and taking the rotatable ball joint as a starting point, installing a plurality of fixed ball joints and a plurality of pull rods in sequence, wherein the vault is installed in a transverse extending manner during the installation of the ball joints and the pull rods, and a lifting device lifts an extension tail end of the vault during the transverse extending process of the vault, so that a height of the extension tail end is maintained at a ground level to allow ground installation construction. 